Age important factor in fertility treatment

January 15, 2009 3:02:37 PM PST

January 15, 2009 --

Age can make a big difference when it comes to the success of a popular fertility treatment. For couples who are having trouble getting pregnant, in vitro fertilization methods, or IVF, can prove highly successful.

But new research warns IVF has limits and it's success rate drops with the increase of a woman's age.

A study in the New England Journal of Medicine tracked more than 6,000 women undergoing IVF. At least half gave birth to a baby, but the success rate jumped to 65 percent if the women were younger than 35. This number dropped to just 23 percent for women over 40.

Doctors say, because time is of the essence, women older than 40 should wait no longer than six months.